Charlie Somerville, developing the operating system as a hobby in Rust language, funny, but quite a working project (DSL), presented as an alternative to the WSL (Windows Subsystem for Linux) subsystem developed by Microsoft for those who prefer to work in DOS. Like WSL, the DSL subsystem allows you to run Linux applications directly, but not from Windows, but from an MS-DOS or FreeDOS command shell. Subsystem source code licensed under AGPLv3.
A DOS environment with a DSL layer can be either launched in the form of a QEMU virtual machine or installed on . Linux programs are launched using the dsl utility, similar to the wsl utility. The implementation of the project is based on the fact that Linux leaves the first megabyte of memory untouched during the boot process. This memory is used by DOS, so the DOS and Linux environments do not overlap and can coexist. The DSL's job is to organize a switch to Linux and return control to DOS after the process is completed, similar to how the work of early versions of Windows was organized.
Source: opennet.ru